Faults appear occasionally, also in the most high-quality communication systems. Many types of faults do mainly affect only the node in which it is situated. However, faults occurring in the receiving signal chain may influence quality or capacity also in other parts of the communication system. A fault in the reception of a signal may in many situations be interpreted just as a signal having poor radio conditions. Means for regulating powers and interference levels are available in many systems today, and such a fault may thus result in increased use of power, higher interference levels and eventually lower useful transmission resources.
In some systems of today, equipment is tested for faults by separate testing routines. However, such testing events also reduce the total available transmission resources. Large faults can be detected by sudden interruptions in the normal traffic. However, smaller faults or non-optimum operation of different parts are more difficult to find. Also, when a fault is known to be present in a receiving signal chain, it typically takes some efforts to localize where in the chain the fault appears.
A general problem in prior art wireless communication systems is thus that supervision and fault detection often is insufficient.